粘土矿物成因及对砂岩储集性能的影响

INFLUENCE OF CLAY MINERALS ONSANDSTONE RESERVOIR PROPERTIES

粘土矿物是影响砂岩储集性能的重要因素。结合实例讨论了粘土矿物成因、绝对含量、成分、产状及晶体形态等与砂岩储集性能的关系。研究表明 ,粘土矿物对砂岩储集性能的影响程度与砂岩本身的成熟度有关。当砂岩成熟度高时 ,随粘土矿物绝对含量的增加 ,其储集性能降低 ,尤其是渗透率降低 ;但高成熟度砂岩随高岭石和充填状粘土矿物含量增高 ,物性相对变好。当砂岩的结构和成分成熟度比较低时 ,粘土矿物对其储集物性影响较小 ,而主要与岩石本身的成分和结构有关。研究还表明 ,不同形态的伊利石对砂岩的物性影响也不同 ,片状伊利石有利于改善储层物性 ,而纤维状和发丝状伊利石增多会使砂岩储集物性降低或变为非储层。

It is well known that clay minerals are the important factor that controls sandstone reservoir properties. This paper discussed clay mineral genesis of sandstone reservoir in Tarim and Shaanxi-Gansu-Ningxia basin. Study on the relationship of reservoir properties with content, occurrence and crystalline form of clay minerals was also carried out. The results show that the influence of clay mineral on the sandstone properties associates with sandstone maturation. The influence is significant on high maturation sandstone, and it is slight on low maturation sandstone. The high maturation sandstone properties degrade with the increase of clay mineral content, especially, permeability, and it is enhanced by the increase of kaolinite and filling state clay mineral content. The results also show the influence of three illinite crystalline forms on sandstone properties is different. Sheet like illinite is favourable to sandstone properties, while fibrous and hair form are not.